zeroth law??

zeroth law: "If bodies A and B are in thermal equilibrium with a third body T, then they are in thermal equilibrium with each other."

In less formal language, the message of the zeroth law is:"Every body has a property called temperature. When two bodies are found to be in thermal equilibrium, their temperatures are equal." We can now make our thermoscope (body T) into a thermometer, confident that its readings will have physical meaning. All that we have to do is calibrate it.

Approved